Soldering, spot welding, or brazing is used for joining structural materials having a large joint surface, such as a heatsink or an automotive body.
Since a solder has properties of gathering in a place where wettability is high during heating and melting, it is difficult to join large joint surfaces together, and there is typically no other choice but to employ joining in the form of spot welding. Further, in the spot welding, from the characteristic of its process, a joint portion exists in the form of dots, and surface joining is difficult. As described above, since both soldering and spot welding become joining in the form of spot, there is a concern that joint strength decreases.
On the other hand, in brazing, surface joining can be implemented since a wax is spread across a joint surface. However, since a joining temperature of brazing is high, there are concerns about deleterious effects such as deformation or embrittlement of surrounding members. The spot welding is similar in that a joining temperature is high, and there are concerns about the same deleterious effects as in brazing. Further, in the spot welding, there is a concern that expensive facilities are required.
Patent Document 1 discloses an alloy joining material capable of being alternative to a high-temperature based solder, and a joining method using the same. In this technique, metal members of Ni, Ag or Al are joined together with an alloy joining material including Te and Ag as main components, and an additive such as Sn or Zn interposed between the metal members, and joined metal members are heat-treated at about 350 to 450° C. Thereby, two metal members are joined together with a joint layer including a Te—Ag alloy and having high heat resistance interposed between the two metal members.
Patent Document 1: JP-A No. 2008-238233